I`d like to help you a bit but my englisch is not so good.
So i have some ideas like a survival level ,some ships for both sides
or new vehicles and units like rebells from umbara or a z95 headhunter
or ashoka with 2 lightswords.
I like also a level on kamino, where you have to defend Kamino from a huge wave of droids in space and ground.And many more ideas.
So i hope this can help you a bit.